1 /* 2 * Copyright (c) 2001 Damien Miller. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 23 */ 24 25 #include "includes.h" 26 27 #define RANDOM_SEED_SIZE 48 28 29 #ifdef WITH_OPENSSL 30 31 #include <sys/types.h> 32 #include <sys/socket.h> 33 #ifdef HAVE_SYS_UN_H 34 # include <sys/un.h> 35 #endif 36 37 #include <netinet/in.h> 38 #include <arpa/inet.h> 39 40 #include <errno.h> 41 #include <signal.h> 42 #include <string.h> 43 #include <unistd.h> 44 #include <stddef.h> /* for offsetof */ 45 46 #include <openssl/rand.h> 47 #include <openssl/crypto.h> 48 #include <openssl/err.h> 49 50 #include "openbsd-compat/openssl-compat.h" 51 52 #include "ssh.h" 53 #include "misc.h" 54 #include "xmalloc.h" 55 #include "atomicio.h" 56 #include "pathnames.h" 57 #include "log.h" 58 #include "sshbuf.h" 59 #include "ssherr.h" 60 61 /* 62 * Portable OpenSSH PRNG seeding: 63 * If OpenSSL has not "internally seeded" itself (e.g. pulled data from 64 * /dev/random), then collect RANDOM_SEED_SIZE bytes of randomness from 65 * PRNGd. 66 */ 67 #ifndef OPENSSL_PRNG_ONLY 68 69 /* 70 * Collect 'len' bytes of entropy into 'buf' from PRNGD/EGD daemon 71 * listening either on 'tcp_port', or via Unix domain socket at * 72 * 'socket_path'. 73 * Either a non-zero tcp_port or a non-null socket_path must be 74 * supplied. 75 * Returns 0 on success, -1 on error 76 */ 77 int 78 get_random_bytes_prngd(unsigned char *buf, int len, 79 unsigned short tcp_port, char *socket_path) 80 { 81 int fd, addr_len, rval, errors; 82 u_char msg[2]; 83 struct sockaddr_storage addr; 84 struct sockaddr_in *addr_in = (struct sockaddr_in *)&addr; 85 struct sockaddr_un *addr_un = (struct sockaddr_un *)&addr; 86 mysig_t old_sigpipe; 87 88 /* Sanity checks */ 89 if (socket_path == NULL && tcp_port == 0) 90 fatal("You must specify a port or a socket"); 91 if (socket_path != NULL && 92 strlen(socket_path) >= sizeof(addr_un->sun_path)) 93 fatal("Random pool path is too long"); 94 if (len <= 0 || len > 255) 95 fatal("Too many bytes (%d) to read from PRNGD", len); 96 97 memset(&addr, '\0', sizeof(addr)); 98 99 if (tcp_port != 0) { 100 addr_in->sin_family = AF_INET; 101 addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK); 102 addr_in->sin_port = htons(tcp_port); 103 addr_len = sizeof(*addr_in); 104 } else { 105 addr_un->sun_family = AF_UNIX; 106 strlcpy(addr_un->sun_path, socket_path, 107 sizeof(addr_un->sun_path)); 108 addr_len = offsetof(struct sockaddr_un, sun_path) + 109 strlen(socket_path) + 1; 110 } 111 112 old_sigpipe = signal(SIGPIPE, SIG_IGN); 113 114 errors = 0; 115 rval = -1; 116 reopen: 117 fd = socket(addr.ss_family, SOCK_STREAM, 0); 118 if (fd == -1) { 119 error("Couldn't create socket: %s", strerror(errno)); 120 goto done; 121 } 122 123 if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) { 124 if (tcp_port != 0) { 125 error("Couldn't connect to PRNGD port %d: %s", 126 tcp_port, strerror(errno)); 127 } else { 128 error("Couldn't connect to PRNGD socket \"%s\": %s", 129 addr_un->sun_path, strerror(errno)); 130 } 131 goto done; 132 } 133 134 /* Send blocking read request to PRNGD */ 135 msg[0] = 0x02; 136 msg[1] = len; 137 138 if (atomicio(vwrite, fd, msg, sizeof(msg)) != sizeof(msg)) { 139 if (errno == EPIPE && errors < 10) { 140 close(fd); 141 errors++; 142 goto reopen; 143 } 144 error("Couldn't write to PRNGD socket: %s", 145 strerror(errno)); 146 goto done; 147 } 148 149 if (atomicio(read, fd, buf, len) != (size_t)len) { 150 if (errno == EPIPE && errors < 10) { 151 close(fd); 152 errors++; 153 goto reopen; 154 } 155 error("Couldn't read from PRNGD socket: %s", 156 strerror(errno)); 157 goto done; 158 } 159 160 rval = 0; 161 done: 162 signal(SIGPIPE, old_sigpipe); 163 if (fd != -1) 164 close(fd); 165 return rval; 166 } 167 168 static int 169 seed_from_prngd(unsigned char *buf, size_t bytes) 170 { 171 #ifdef PRNGD_PORT 172 debug("trying egd/prngd port %d", PRNGD_PORT); 173 if (get_random_bytes_prngd(buf, bytes, PRNGD_PORT, NULL) == 0) 174 return 0; 175 #endif 176 #ifdef PRNGD_SOCKET 177 debug("trying egd/prngd socket %s", PRNGD_SOCKET); 178 if (get_random_bytes_prngd(buf, bytes, 0, PRNGD_SOCKET) == 0) 179 return 0; 180 #endif 181 return -1; 182 } 183 184 void 185 rexec_send_rng_seed(struct sshbuf *m) 186 { 187 u_char buf[RANDOM_SEED_SIZE]; 188 size_t len = sizeof(buf); 189 int r; 190 191 if (RAND_bytes(buf, sizeof(buf)) <= 0) { 192 error("Couldn't obtain random bytes (error %ld)", 193 ERR_get_error()); 194 len = 0; 195 } 196 if ((r = sshbuf_put_string(m, buf, len)) != 0) 197 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 198 explicit_bzero(buf, sizeof(buf)); 199 } 200 201 void 202 rexec_recv_rng_seed(struct sshbuf *m) 203 { 204 u_char *buf = NULL; 205 size_t len = 0; 206 int r; 207 208 if ((r = sshbuf_get_string_direct(m, &buf, &len)) != 0 209 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 210 211 debug3("rexec_recv_rng_seed: seeding rng with %u bytes", len); 212 RAND_add(buf, len, len); 213 } 214 #endif /* OPENSSL_PRNG_ONLY */ 215 216 void 217 seed_rng(void) 218 { 219 unsigned char buf[RANDOM_SEED_SIZE]; 220 221 /* Initialise libcrypto */ 222 ssh_libcrypto_init(); 223 224 if (!ssh_compatible_openssl(OPENSSL_VERSION_NUMBER, 225 OpenSSL_version_num())) 226 fatal("OpenSSL version mismatch. Built against %lx, you " 227 "have %lx", (u_long)OPENSSL_VERSION_NUMBER, 228 OpenSSL_version_num()); 229 230 #ifndef OPENSSL_PRNG_ONLY 231 if (RAND_status() == 1) 232 debug3("RNG is ready, skipping seeding"); 233 else { 234 if (seed_from_prngd(buf, sizeof(buf)) == -1) 235 fatal("Could not obtain seed from PRNGd"); 236 RAND_add(buf, sizeof(buf), sizeof(buf)); 237 } 238 #endif /* OPENSSL_PRNG_ONLY */ 239 240 if (RAND_status() != 1) 241 fatal("PRNG is not seeded"); 242 243 /* Ensure arc4random() is primed */ 244 arc4random_buf(buf, sizeof(buf)); 245 explicit_bzero(buf, sizeof(buf)); 246 } 247 248 #else /* WITH_OPENSSL */ 249 250 /* Acutal initialisation is handled in arc4random() */ 251 void 252 seed_rng(void) 253 { 254 unsigned char buf[RANDOM_SEED_SIZE]; 255 256 /* Ensure arc4random() is primed */ 257 arc4random_buf(buf, sizeof(buf)); 258 explicit_bzero(buf, sizeof(buf)); 259 } 260 261 #endif /* WITH_OPENSSL */ 262